For Physicians: Cutaneous Nerve Biopsy and Analysis
Physicians can schedule patients for cutaneous nerve skin biopsies at Johns Hopkins without a separate new patient consultation visit. Call 410-502-7930.
You can also perform skin punch biopsies in your office and send the tissue samples to our lab for processing and interpretation.
The process is simple. Here are step-by-step instructions:
- Submit patient information and order a kit
- Perform the biopsy
- Ship the biopsy
- Teach patient proper site care
Submit Patient Information and Request a Test Kit
To order a biopsy kit, please call 410-955-3254 or email [email protected]. The kit contains the following:
- Tubes of Zambonis fixative
- Requisition card to be completed
- Quick reference card with biopsy and shipping instructions
- Prepaid FEDEX clinical pack for return shipment
- Patient care kit containing bandages and wound care instructions to give to patients
- Physician kit containing:
- 3mm punch biopsy tool
- Suture removal kit
- Biopsy tube labels
- Gauze
- Alcohol wipes
- Bandages
Please note that the following supplies are NOT part of the kit, but will be needed to complete the skin biopsy:
- Injectable local anesthetic
- Syringe
- Gloves
- Tape measure
- Skin marker
Performing the Biopsy
Standard biopsy sites are distal leg, distal thigh and proximal thigh.
A cutaneous nerve/skin biopsy is a very simple procedure that takes 10 to 15 minutes and is performed in an outpatient setting.
- The skin is thoroughly cleaned and a small injection of a local anesthetic to numb the skin is made.
- A sample of skin is taken by a biopsy from the numb area of the skin.
- A band-aid dressing is used to cover the biopsy site.
Generally, the skin heals easily within one to two weeks. The risk of bleeding or infection is extremely low.
Patients who are anticoagulated with INR > 2.5 should not have the biopsy.
Steps to Perform a Cutaneous Nerve/Skin Biopsy
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After the patient has been gowned, a clinical history has been taken, and the procedure explained, the area of skin where the biopsy is to be performed is prepared with an alcohol swab to insure sterile conditions. -
Once the skin has been prepared with alcohol, the next step is to anesthetize the area to be biopsied by injecting a solution of Lidocaine (HCL 1% and Epinephrine 1:100,000) just under the epidermis (subepidermally) using a ½ cc Tuberculin Syringe. The injection should continue until a “bleb” or bubble has formed under the skin greater than 3mm in diameter. The injection will burn slightly (much like a bee sting) due to a pH difference between the skin and the solution. The slight burning will quickly subside and the site will become numb. -
After the initial Lidocaine injection the area to be biopsied should be checked to insure that the skin is properly anesthetized. The point of the syringe is used to poke the area of the bleb or bubble. Great care should be taken not to force the needle into the skin. The test site should be somewhere around the periphery of the bleb. Both of these precautions insure a viable biopsy for diagnosis later. If the patient experiences neither pain nor sharp sensation, the biopsy continues. A pressure sensation is normal and expected but there should be no pain. If the area requires more anesthesia, another injection (with a new syringe) is made until the skin is completely anesthetic. -
After the area to be biopsied is anesthetized, the biopsy continues. Using a sterile 3mm skin punch, the physician applies pressure and twisting in a “drilling” motion until the blade of the skin punch has pierced the epidermis of the skin. The blade should be about ½ exposed. It is normal for the patient to experience a pressure and twisting sensation but no pain. -
After the blade has sufficiently “cored” or carved out a 3mm cylinder of skin the skin punch is removed. It is normal for the area to bleed after the punch is removed. Excess blood is wiped off with sterile 2 x 2 gauze to expose the biopsy site. The entire process resembles the “cookie cutter” effect. The only purpose of the skin punch is to “core” the skin and not to remove the biopsy, much like a cookie cutter. -
When the skin has been cored and cleared of excess blood, the next step is to remove the biopsy from the rest of the skin. Great care should be taken not to damage the epidermis by crushing it with forceps or by cutting it with a scalpel unnecessarily. The physician uses the forceps to grab the dermis of the cored skin, pulls up the core to reveal excess dermis and subdermal fat, and uses the scalpel in one or two cutting motions to cut the cored skin free. -
Notice the position of the scalpel during the excision process. The scalpel is placed under the forceps and is moved in the opposite direction of the forceps pulling on the dermis. This motion stabilizes the biopsy and aids in preventing a “chopping” or “slicing” affect when trying to free the biopsy. The physician simply utilizes one or two strokes of the scalpel to excise the biopsy with a clean cut. -
Once the biopsy has been removed from the skin there will usually be some degree of bleeding which should be absorbed with sterile 2 x 2 gauze. The biopsy site is then covered with a standard band-aid and possibly fortified with sterile gauze and paper tape if the bleeding threatens to soak the band-aid and/or the patient’s clothing. This “hole” in the skin will continue to bleed for the rest of the day and may or may not form a scab in a few days time. -
The biopsy site should be kept clean. The site should not be submerged in water (i.e. no swimming, hot tubs, baths, etc.) for a few days. The bandage should be changed at least once a day and should be changed if it should become wet or damp. Once a substantial scab has formed, or new skin begins to grow over the area and bleeding has stopped, the bandage can be removed. In the long term, minimal scaring may occur. In most cases the biopsy site is indistinguishable within a few months. In a few instances the biopsy site may form a protrusion or bump but continue to heal normally.
Biopsy Shipping Instructions
Please follow the guidelines below for proper shipping instructions and related information.
- Do not ship specimens on Friday, Saturday, Sunday or the day before a major holiday. If in doubt, contact us at 410-502-7930.
- Place labeled specimen tubes in the leak-proof plastic bag provided with the shipping kit.
- Place the plastic bag into the brown kit box. Then put the brown box and completed requisition form into the FEDEX Clinical Pack with prepaid label.
Contact FEDEX for pickup. Our shipping address is:
Johns Hopkins Cutaneous Nerve Lab
ATTN: Kelly Wagner
The John G Rangos Bldg, Rm 440.11
855 N. Wolfe Street
Baltimore, MD 21205
Phone: 410-955-3254
Patient Instructions for Biopsy Site Care
- Leave your wound dressings in place for the rest of the day of the biopsy and keep them dry.
- Refrain from doing extremely strenuous activity for the rest of the day of your biopsy (such as running or heavy lifting).
- Change band-aids daily starting the day after the biopsy until there are no open wounds. This can take anywhere from 1 or 2 days up to 2 weeks (5-6 days is average for daily band-aid changes).
- The wounds may or may not form a scab as they heal; either is fine.
- Showers are fine starting the day after the biopsy. Leave the band-aids in place while you shower and change them after you dry off.
- During the time period of daily band-aid changes, do not soak in a bath or swim.
- If you need to clean the wounds, you can use hydrogen peroxide. If the wounds are fine (no signs of infection), a daily band-aid change is all you need.
- The local anesthetic used for the biopsy will usually last for 1 to 2 hours after the procedure. After it wears off, you may have some mild localized soreness and tenderness at the biopsy sites over the next day or two. You may find regular Tylenol is helpful for the discomfort.
- Once the biopsy sites heal, they may look slightly red or darker than the rest of the skin. This discoloration will gradually fade and blend with your normal skin color. This fading process may take anywhere from a few months up to a year.
- Problems during the healing period are very rare. It is normal for the biopsy sites to bleed a little or drain pink fluid for a day or two after the procedure. They should not bleed excessively (i.e., through the band-aid) after that time. They should never drain pus. If you experience problems with significant bleeding, redness, infection or other problems, call your doctor's office.